<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>类选择器</title>
    <style type="text/css">
        .red {color:red;}
        .green {color:green;}
        .font22 {font-size:22px;}
        p {
            text-decoration:underline;
            font-family:"微软雅黑";
        }
    </style>
</head>
<body>
    <h2 class="red">二级标题文本</h2>
    <p class="green font22">段落一文本内容</p >
    <p class="red font22">段落二文本内容</p >
    <p>段落三文本内容</p >
</body>
</html>